Laser induced graphitization of PAN-based carbon fibers

laser. After laser graphitization, the surface and cross-section structure were characterized by Raman spectroscopy. As the power density increased, a profound increase of graphitization degree happened and obvious skin-core structures were observed. Furthermore, the results of XPS measurements indicated that the irradiated CFs showed more conjugated structures. For crystallite structure, the interlayer spacing of the (002) lattice decreased and the thickness of crystallite increased after graphitization. The size of the (002) lattice parallel to the fiber axis changed slightly. The surface morphology was also investigated by SEM, sheet structures and particles could be observed on the surface of CFs. This was attributed to fast energy addition of laser and the characteristics of the material. Further HRTEM investigation revealed that the sheet structure is multilayered graphene. The Young's modulus of irradiated fibers showed obvious improvements compared to that of as-received ones.